joigus

Thanks for your interest. Your numbers 1, 2, and 6 are in my heart too. Another one is American biologist Barbara McClintock, discoverer of transposable genes.

LOL.

She must have been a great teacher! Edit: I'll never forget Mercedes Serra, she taught me maths and physics. I wonder what became of her.

Cometh the comedian, cometh the comedown. And cometh the comet, cometh the final homecoming. You still haven't told me your favourite woman in science, DR.

"Fighting" encompasses so many things... You forgot to tell me your favourite woman in science, @dimreepr.

You're right, but until that day comes...

To all women @SFN, and to all women in science: Happy Women's Day!! We value you, trust you, we love your work, and we wish you to keep going strong. Most importantly: We are inspired by you. You're better off without a Y chromosome, believe me. What's your favourite woman in science? Mine is Emmy Noether.

Yes, I'm sorry too, because now I realise I wasn't clear. I meant there may be even more redundancies further down the line replication --> transcription --> translation. And by XYZ... I meant the protein, that is, the sequence of aminoacids. Suppose the nucleotide sequence codes for a particular protein, instead of a transcription factor, or a protein that needs to fold in a very precise way at the level of beta structure, etc., like, eg. hemoglobin. Just a simple alpha-structure completely boring structural chain. So in that case there would be even more redundancy at the "production line" level, so to speak. For some proteins it could be the case that cutting (splicing) here or there doesn't really make that much of a difference. By XYZ I should have specified valine-glycine-whatever. In some proteins the Y aminoacid (say it's hydrophobic) could be just fine if you simply replace it by another hydrophobic aminoacid and everything would be OK structurally. Even if it's a transcription factor, it could be the case that it binds just a little bit less efficiently by changing one aminoacid, so your equilibrium constant would be displaced just the slightest bit to the left... So you're right. I don't disagree with you. There would be the redundancies that you point out, and maybe even more. In fact I understand redundancies of this kind are essential for there being a possibility of evolution to be so "malleable." It's an interesting discussion, but we're getting off the track...

I was absolutely unaware of this. Thank you. Is this compatible, incompatible, or completely independent (maybe a previous eon) of the RNA-world hypothesis?

I didn't really mean errors in replication. I meant different versions of splicing. And I did say that. Didn't I? Look, I did: Splicing is different. It happens after replication. And mind you, making mistakes in replication could be fatal, but making mistakes in trancription, and even more in translation, is quite innocuous in comparison.* Deletion, insertion and frameshift mutation happen before. But you may be right that it wouldn't be completely inconsequential. Do you happen to know how the hypothetical protein I wrote is going to fold? I'm not sure. That's why I said, That's the whole point I was trying to make. I don't know. Do you know? Gosh! I really do have to have my wits around me when you're there... But thank you. * mRNA degrades very quickly.

You're absolutely right. There's quite a lot of redundancy, including several start/stop codons. There may even be redundancy after splicing, as chains like XYZXYZXYZ are essentially the same as YZXYZXYZX, aren't they? Cyclic symmetries,.... But that's another matter.

Right. As CharonY has said, chemolithotrophs* came before. I overlooked those because I was thinking in terms of a plant/animal dichotomy. Other things came before and probably exploited a wide variety of red-ox reactions. Some organisms "respirated" H2S from volcanoes, but they didn't get a sweet deal in energetic terms, I think. Nothing like the 36-39 ATP mol per glucose mol that eukaryotes get. When it came down, it must have been the goose that laid the golden eggs. * I wonder if chemolithotrophs aren't the real rulers of the universe in terms of sheer abundance in the universe. I bet they are.

Very interesting question. Welcome to SFN. I'm looking forward to expert answers. Viruses/viri are peripheral to life. They need hosts, so they came later. But not much later, as they need much less combinatorics than prokaryotes to go by. There's a certain redundancy in proteins (some proteins can be synthesised from slightly different sequences of nucleic acids). Maybe some sequences of nucleic acids can use deception? Some kind of reverse-redundancy?: They "look" similar to ribosomes polymerases in the binding site, but they execute completely different functions...

You're welcome, and thanks for your appreciation. Both cellular respiration and photosynthesis are very old mechanisms for obtaining energy from the environment. Cellular respiration "sits on top" of fermentation, which is believed to be the oldest game in town. The take-home lesson being: Don't bury mantises in pots.

Infinite in time --although an idealisation-- is OK. "Infinite in space" requires some clarification: 1) Infinite in both the region of space the particle is restricted to move, and the proper length parameter (usually called s) 2) Finite in space (region where your particle is restricted to move) but infinite in the proper length parameter even though the particle may cover a trajectory over and over again (periodic motion) Your 2nd case corresponds to my 2nd case. In your 3rd case, the motion is finite in space and in the proper length parameter, but infinite in time in the mathematical ideal case. A good example is a particle moving in a viscous fluid. In the ideal case, the particle velocity is a decreasing exponential, and it would ideally take infinite time for the particle to stop. What one does in a practical case is to set up a time T such that the ratio between the particle velocity at time T and the limit velocity has gone down to a level that you would consider that it has effectively come to a halt. Say, \[ \frac{v\left(T\right)}{v\left(\infty\right)}<.99 \] where \( v\left(\infty\right) \) is the limit velocity. So, as @swansont said, the 3rd case is finite in space. It's also finite in time for all practical purposes. And in the real case too, as the velocity is well below the level of statistical fluctuations at some point.

Very nice. I think those fish are feasting on some stuff...

There's always a bad apple, isn't there? In this case a bad rafflesia. Very interesting.

Sorry I haven't been very helpful. To give you an idea of how central it is whether an element is a metal or not, or how much of a metal it is, is absolutely central to chemistry, here's a snapshot of the periodic table. Alkaline (also called alkali metals) Non-metals Other metals Transition metal Metalloid Rare earth Alkalie metal Halogen Nobel gas The concept of metal is so central to chemistry that you could understand a lot of what chemistry is about focusing on the concept. You would miss another important central concept, which is acid/base, and has to do with transfer of protons, rather than electrons.

They don't have chloroplasts. Even liverworts and mosses (the most primitive plants that still exist) have chloroplasts. Do mantises have chloroplasts? And That's why they're not autotrophs: They don't synthesise sugar from CO2, consuming water. Animalia (cellular respiration): C6H12O6 + 6O2 --> 6CO2 + 6H2O (many intermediate steps omitted) Plants: Cellular respiration plus, Photosynthesis: 6CO2 + 6H2O --> C6H12O6 + 6O2 which is (overall and oversimplifying) the inverse of cellular respiration. LOL. x-posted with @Genady

Not really that much of an insight TBH, but I'll take it anyway. Baez-Dolan cobordism hypothesis is used to clasify topological quantum field theories. What does it have to do with computation? I'm familiar with Baez's motto "A QFT is a functor." However interesting such statements may be in physics, what do these manifolds represent in computer science? Topological information on a manifold could be coded in topological invariants, like, ie., the Betti numbers. Is that the connection? Thank you, but no, thank you. I spent three months studying those under a teacher who was a mathematical physicist. Very nice, very good teacher. A fountain of mathematical knowledge in the vein of Baez. I thank him for the A he gave me, which I didn't deserve. But I don't know what the hell we were doing studying monoids and alphabets as a substitute for group theory for physicists. Apparently, no one in the department wanted to teach the Lorentz group because it's not compact, and that's very very bad, for some reason. I had to learn that from Weinberg's QFT Volume I. I tell you this just to explain I'm a person very much shaped by the effort of trying to free myself from the shackles of being exposed to layers and layers of abstraction that don't lead anywhere useful. As to, I don't know what to do with that, or in what sense it clarifies what information is, or how it's stored, deleted, encrypted, etc. It certainly doesn't clarify Landauer's principle to me. You might as well have given me the procedure to pluck a chicken. What particular aspect does it clarify in information theory? That's what I call an insight.

Yes, Giant Technicolor Squirrels Actually Roam the Forests of Southern India: https://www.smithsonianmag.com/smart-news/yes-giant-technicolor-squirrels-actually-roam-forests-southern-india-180971886/ Surreal Frozen Lake Michigan Turns Into a Magical Wonderland https://www.beautyofplanet.com/surreal-frozen-lake-michigan-turns-into-a-magical-wonderland/?fbclid=IwAR2nGvee4LVegUc7Y-2XD9gi6N2DaRmKKb-pP0A2EoIZ5mPSVUVgGs9sYsI

No, no. You go. I took Chemistry 101 many years ago. You tell me. 😇

It's statements like these that are a real timesaver for me when pondering whether to follow a certain line of reasoning. Thank you so much.

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I'm going to build an argument that's completely isomorphic to this --no matter how scholarly-- silly idea: If sacrificing a virgin is the only means of avoiding a natural catastrophe that would wipe out thousands of lives, sacrificing a virgin should be used --and will be used-- to obtain the desired results... No one who doubts that this is the case should be in a position of responsibility. Another isomorphism: A chain is as strong as its weakest link. An argument is as weak as the validity of the "if" it rests on.